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iladlc.go
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/
iladlc.go
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// Copyright ©2015 The gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package native
// Iladlc scans a matrix for its last non-zero column. Returns -1 if the matrix
// is all zeros.
func (Implementation) Iladlc(m, n int, a []float64, lda int) int {
if n == 0 || m == 0 {
return n - 1
}
checkMatrix(m, n, a, lda)
// Test common case where corner is non-zero.
if a[n-1] != 0 || a[(m-1)*lda+(n-1)] != 0 {
return n - 1
}
// Scan each row tracking the highest column seen.
highest := -1
for i := 0; i < m; i++ {
for j := n - 1; j >= 0; j-- {
if a[i*lda+j] != 0 {
highest = max(highest, j)
break
}
}
}
return highest
}